Concentric annular tanks

ABSTRACT

Concentric annular tanks for the storage of solutions containing fissile materials are disclosed. By placing an appropriate neutron isolator between each of the annular tanks, a critical fissile mass can be avoided and additional annular tanks can be added to achieve a desired total volume and maximum floor space usage. In one embodiment the individual tanks are communicatively coupled at at least one location to equalize the fluid level within the corresponding tanks. The couplings are adaptable for the accession of additional concentric annular tanks to accommodate a larger storage volume.

United States Patent Siemens, Jr.

[ 1 May 6,1975

[ CONCENTRIC ANNULAR TANKS [75] Inventor: Dan H. Siemens, Jr., Richland,

Wash.

[73] Assignee: Westinghouse Electric Corporation,

Pittsburgh. Pa.

221 Filed: Nov. 1, 1972 [21] Appl. No.: 304,452

[52] US. Cl 250/507; 250/518; 252/3011 W [51] Int. Cl. G2 1/00 {58]Field of Search 250/506, 507, 518, 526, 250/30l.1 W

[56] References Cited UNITED STATES PATENTS 2,918,717 12/1959 Struxmesset a1 250/3011 W 3,046,403 7/1962 Montgomery 250/507 3,056,028 9/1962Mattingly 250/518 3,101,258 8/1963 Johnson 252/301.l W

Rogers 250/506 Schlies 250/507 Primary ExaminerHarold A. Dixon Attorney,Agent, or FirrnD. C. Abeles [5 7 1 ABSTRACT Concentric annular tanks forthe storage of solutions containing fissile materials are disclosed. Byplacing an appropriate neutron isolator between each of the annulartanks, a critical fissile mass can be avoided and additional annulartanks can be added to achieve a desired total volume and maximum floorspace us age. In one embodiment the individual tanks are communicativelycoupled at at least one location to equalize the fluid level within thecorresponding tanks. The couplings are adaptable for the accession ofadditional concentric annular tanks to accommodate a larger storagevolume.

8 Claims, 3 Drawing Figures PATENTEUMAY ems SHEU 10$ 2 PATENIEDm e|szsSHEET 2 BF 2 FIG.2.

CONCENTRIC ANNULAR TANKS BACKGROUND OF THE INVENTION This inventionpertains in general to annular storage tanks and more particularly. toconcentric annular storage tanks with isolation for the storage ofsolutions containing fissile nuclear material.

In the nuclear processing industry it is often neces sary to providetanks for large volumes containing reactive nuclear material. If thesesolutions contain fissile material. a geometrically favorable design isrequired. One geometrically favorable design is a narrow rectangulartank which is commonly referred to as a slabtank. The slab width isdictated by the amount of fissile material present in the storagesolution and is normally less than five inches. The main objective indesigning the slab width is to avoid criticality. As a result, theslab-tank configuration is impractical when a volume capacity of morethan 1,000 liters is desired, due to the extensive amount of floor spacerequired to accommodate the larger volume. Additionally, a largeslab-tank is more costly to construct because it requires massivestiffeners to provide structural strength and prevent distortion understress which could cause the critical slab dimension to change. Anothergeometrically favorable design is an annular tank. Here again, theannular width of the storage volume is dictated by the fissile materialcontent of the storage solution and is normally less than five inches.There is no limit to the diameter that an annular tank can beconstructed. however, there is a waste of floor space inside the annularopening of the tank. Furthermore, an annular tank easily accommodatesmoderate changes in internal pressure. or vacuum, without distortion ofthe critical dimension.

Accordingly, an optimized geometrical structural de sign is desired forsuch tanks that will provide the desired total volume storage capacityrequired by the nuclear industry while maximizing floor space usage.

SUMMARY OF THE INVENTION Briefly, this invention provides an optimizedstructural geometry for containment tanks employed in the storage ofsolutions containing nuclear material. In accordance with thisinvention, concentric annular tanks are described with neutron isolatorspositioned between each of the respective tanks. The isolators aredesigned to have a sufficient neutron capture crosssection to guardagainst the formation of a critical mass of nuclear material. Additionalannular tanks can be added concentrically to achieve a desired totalvolume and maximum floor space usage. In one embodiment, the individualtanks are communicatively coupled at at least one location to equalizethe fluid level within corresponding tanks. The couplings are adaptablefor the accession of additional concentric annular tanks to accommodatelarger storage volumes while minimizing floor space usage.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of theinvention, reference may be had to the preferred embodiment, exemplaryof the invention, shown in the accompanying drawings, in which:

FIG. 1 is a planned view of one embodiment of this invention;

FIG. 2 is an elevational sectional view of the embodiment illustrated inFIG. I; and

FIG. 3 is a sectional view of the embodiment of FIG. I illustrating theaccession of additional annular concentric tanks.

DESCRIPTION OF THE PREFERRED EMBODIMENT An optimized structural geometrycontemplated by this invention for containment tanks applicable for thestorage of solutions containing fissile material is illustrated inFIGS. 1. 2 and 3, which show an annular tank design where two, three, ormore tanks are arranged concentrically to achieve a more economical useof floor space. By placing an appropriate neutron isolator between eachof the annular tanks, additional annular tanks can be added to achieve adesired total volume and maximum floor space usage.

Referring to FIG. I it can be observed that a planned view is providedof a concentric array of two annular tanks exemplary of this invention.An outer hollow annular tank is shown and generally described byreference character 10. The storage area is defined by the tubularinside and outside walls 14 and I2, respectively, which areconcentrically formed with a bottom plate sealably affixed therebetweenat one end of the corresponding tubular end terminations. The wallthicknesses of the tanks are desirably chosen to accommodate externalpressures without the need for stiffness and to provide sufficientshielding against radioactivity. An exemplary thickness from 0.250 to0.375 inches will provide adequate strength for external pressures up toone atmosphere where materials such as 304L stainless steel areemployed. Type 304L stainless steel is described as an exemplarymaterial for the tank walls due to its compatibility with the elementsto be stored.

An annular isolator I6 is closely received within the annular openingformed by the tubular wall 14 and is designed from a material that has asufficient neutron capture cross section to avoid the formation of acritical nuclear mass. In other words, the annular isolator is designedto absorb a sufficient number of delayed neutrons emitted from theelements being contained within the tank 10 and any number of innerconcentric tanks to avoid a chain reaction from being sustained. Theisolator I6 can be fabricated from any material exemplifying thesedesired characteristics such as serpentine concrete that has a 10percent minimum water content. Each isolator can be desirably jacketedwith eighteen gage stainless steel to prevent absorption of plutoniuminto the concrete (where plutonium is among the materials being stored)and to facilitate de contamination after storage.

A second annular tank is concentrically positioned within the annularopening formed by the outer isolator 16 to achieve a higher densityusage of floor space. The storage area of the second hollow annular tankI8 is specifically defined by the inner and outer tubular walls 22 and20, respectively, with a bottom plate sealably affixed therebetween atone of the corresponding tubular end terminations. The thickness of thetank defined by the difference in radial dimensions between the innerand outer walls is dictated by the fissile material content of thesolution being stored and is normally less than five inches.

A second annular isolator is concentrically positioned within theannular opening formed by the inner tubular wall 22 of the second tank18. This inner isolator 24 is substantially identical to the isolatorpreviously described and defined by reference character [6 and providesa sufficient neutron capture cross section to prevent the delay neutronsemitted from the inner circumference of the tank 18 from sustaining achain reaction.

Referring now to FIG. 2 it will be observed that an elevationalsectional view of the annular tanks of FIG. I is presented. The bottomplates. sealably affixed to the respective side walls of the inner andouter tanks previously described with reference to FIG. 1. areillustrated by reference characters 40 and 38, respectively. Inaddition. the tanks are provided with cover plates 30 and 32 and fluidvents 34 and 36 which are employed to aid in charging the tanks with thematerials to be stored. The tanks can either be filled through inletssimilar to those described by the vents 34 and 36 or through conduitmeans 28 which communicatively couples the interior of tank with theexterior thereof. Optional conduit means 26 can additionally be providedto communicatively couple the respective storage volumes of tanks 10 and18 to equalize the level of storage material within the correspondingtanks. The fluid coupling conduit 26 is desirably designed to disconnectfrom the respective tanks so that the individual tanks can be usedseparately where desired. Furthermore. conduit means 28 is designed forinterconnection to a third annular tank which can be circumferentiallypositioned around tank 10 to form a concentric array of three annulartanks with an increase in storage volume and a maximum usage of floorspace. With the third tank connected as described conduit means 28 willperform the same function as fluid conducting means 26. Similarly,additional annular tanks can be added. either circumferentially orconcentrically, to achieve any desired storage volume.

In the embodiment illustrated the lower plates 40 and 38. which form thebottom walls of the tanks 18 and 10, respectively. are sloped in adirection to assist gravity feed of the storage material through fluidconduit means 26 to conduit 28. Such a structural configuration isdesirable where conduit 28 is designed as an exit port to empty thetanks when the storage period has expired. Furthermore. the respectiveconduits 26 and 28 can be provided with valve closure means to controlor shut off the volume of fluid flow of storage material.

FIG. 3 illustrates a sectional view of an array of concentric annulartanks similar to the array previously described with reference to FIGS.1 and 2. By the addition of a third annular isolator positioned aroundthe periphery of the tank 10 and a third tank positioned in a similarmanner around the periphery of the third annular isolator additionalstorage volume can be ob mined as previously described.

Thus. this invention provides an optimized structural geometry forcontainment tanks designed for the storage of solutions containingnuclear material. enabling a maximum usage of floor space; moreefficient mixing of the storage material; standardization of fabricationtechniques; and added structural support.

l claim as my invention:

1. Concentric annular tanks with isolation for the storage of solutionscontaining nuclear materials comprising:

a first annular hollow tank having a tubular inside and outside wallconcentrically formed with a bottom plate sealably affixed therebetweenat one of the corresponding tubular end terminations so as to form thebottom wall thereof;

a second annular hollow tank having a tubular inside and outside wallconcentrically formed with a bottom plate sealably affixed therebetweenat one of the corresponding tubular end terminations so as to form thebottom wall thereof. said second tank being concentrically positionedwithin the interior annular opening formed by said inside wall of saidfirst tank; and

isolation means associated with said first and second tanks having aneutron capture cross section sufficient to guard against the formationof a critical mass of nuclear material between the storage contents ofsaid first and second tanks.

2. The concentric annular tanks of claim 1 including fluid couplingmeans positioned substantially adjacent the corresponding bottom wallsof the said first and second tanks and communicatively coupling theinterior of said first tank with the interior of said second tank.

3. The concentric annular tanks of claim 2 including conduit meansassociated with said outside wall of said first tank substantiallyadjacent the bottom wall thereof for communicatively coupling theinterior of said first tank with the exterior thereof.

4. The concentric annular tanks of claim 3 wherein said conduit meansand said fluid coupling means are aligned along a common diameter of thecommon annuli of said first and second tanks.

5. The concentric annular tanks of claim 4 including:

a third annular hollow tank having a tubular inside and outside wallconcentrically formed with a bottorn plate sealably affixed therebetweenat one of the corresponding tubular end terminations so as to form thebottom wall thereof, said first tank being concentrically positionedwithin the interior annular opening formed by said inside wall of saidthird tank;

second fluid coupling means associated with said inner wall of saidthird tank substantially adjacent the bottom wall thereof and alignedalong the common diameter of said conduit means. said second fluidcoupling means being adaptable to interconnect with said conduit meansso as to communicatively couple the interior of said first tank with theinterior of said third tank; and

isolation means associated with said first and third tanks having aneutron capture cross section sufficient to guard against the formationof a critical mass of nuclear material between the storage contents ofsaid first and third tanks.

6. The concentric annular tanks of claim 4 wherein said bottom walls ofsaid first and second tanks are sloped along the diameter of saidconduit means in a direction to assist gravity from said second tank tosaid first tank through said fluid coupling means to said conduit means.

7. The concentric annular tanks of claim 1 wherein said isolation meanscomprises an annular casing of concrete closely received between theinner wall of said first tank and the outer wall of said second tank.

8. The concentric annular tanks of claim 1 including a neutron isolatorclosely received within the annular opening formed by the inside wall ofsaid second tank and lining the exterior surface area thereof. saidisolator having a neutron capture cross section sufficient to guardagainst the formation of a critical mass of nuclear material within thestorage contents of said second tank.

1. Concentric annular tanks with isolation for the storage of solutionscontaining nuclear materials comprising: a first annular hollow tankhaving a tubular inside and outside wall concentrically formed with abottom plate sealably affixed therebetween at one of the correspondingtubular end terminations so as to form the bottom wall thereof; a secondannular hollow tank having a tubular inside and outside wallconcentrically formed with a bottom plate sealably affixed therebetweenat one of the corresponding tubular end terminations so as to form thebottom wall thereof, said second tank being concentrically positionedwithin the interior annular opening formed by said inside wall of saidfirst tank; and isolation means associated with said first and secondtanks having a neutron capture cross section sufficient to guard againstthe formation of a critical mass of nuclear material between the storagecontents of said first and second tanks.
 2. The concentric annular tanksof claim 1 including fluid coupling means positioned substanTiallyadjacent the corresponding bottom walls of the said first and secondtanks and communicatively coupling the interior of said first tank withthe interior of said second tank.
 3. The concentric annular tanks ofclaim 2 including conduit means associated with said outside wall ofsaid first tank substantially adjacent the bottom wall thereof forcommunicatively coupling the interior of said first tank with theexterior thereof.
 4. The concentric annular tanks of claim 3 whereinsaid conduit means and said fluid coupling means are aligned along acommon diameter of the common annuli of said first and second tanks. 5.The concentric annular tanks of claim 4 including: a third annularhollow tank having a tubular inside and outside wall concentricallyformed with a bottom plate sealably affixed therebetween at one of thecorresponding tubular end terminations so as to form the bottom wallthereof, said first tank being concentrically positioned within theinterior annular opening formed by said inside wall of said third tank;second fluid coupling means associated with said inner wall of saidthird tank substantially adjacent the bottom wall thereof and alignedalong the common diameter of said conduit means, said second fluidcoupling means being adaptable to interconnect with said conduit meansso as to communicatively couple the interior of said first tank with theinterior of said third tank; and isolation means associated with saidfirst and third tanks having a neutron capture cross section sufficientto guard against the formation of a critical mass of nuclear materialbetween the storage contents of said first and third tanks.
 6. Theconcentric annular tanks of claim 4 wherein said bottom walls of saidfirst and second tanks are sloped along the diameter of said conduitmeans in a direction to assist gravity from said second tank to saidfirst tank through said fluid coupling means to said conduit means. 7.The concentric annular tanks of claim 1 wherein said isolation meanscomprises an annular casing of concrete closely received between theinner wall of said first tank and the outer wall of said second tank. 8.The concentric annular tanks of claim 1 including a neutron isolatorclosely received within the annular opening formed by the inside wall ofsaid second tank and lining the exterior surface area thereof, saidisolator having a neutron capture cross section sufficient to guardagainst the formation of a critical mass of nuclear material within thestorage contents of said second tank.